


Once a Spy

by SlyKermit



Category: And many more but only minorly, Harry Potter - J. K. Rowling, Marvel Cinematic Universe, multifandom
Genre: Born out of a thicc image of Thanos and a subsequent photoshop, Crack, Get cursed folks, I mean you're allowed to but don't blame me, If you take this seriously that's on you, M/M, Snanos, crackship
Language: English
Status: Completed
Published: 2019-10-20
Updated: 2019-10-20
Packaged: 2020-12-27 02:33:53
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 2,749
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21111245
Author URL: https://archiveofourown.org/users/SlyKermit/pseuds/SlyKermit
Summary: The universes have collapsed on top of one another, and so the world is full of dangerously powerful beings. In an attempt to stop Thanos, people turn to the best spy in the whole of Wizarding World - Severus Snape. What ensues, surprises everyone, including the man himself.





	1. The Unlikely Prisoner

**Author's Note:**

> Hiya folks! 
> 
> I would like to take this moment to thank leo and Nerd, whose edits inspired me to create this monstrosity. I would also like to thank Sheriff, who cheered me on, when I proposed writing it in the first place. In other words - this is on you guys as much as it is on me. 
> 
> Enjoy, but please don't take it too seriously, as it is a crack fic. Which is, quite possibly, what I was smoking when I was coming up with it.
> 
> I do not own any of the characters used in this fanfiction.

_ Yet another villain to deal with, _thought Severus, as he forced down the inner voice yelling about how he was lying to himself. Because he wasn’t. Thanos was supposed to be defeated, or at the very least contained, he was supposed to be another Voldemort, but there was nothing Severus could do to make himself believe that. He was so… thoughtful. Cold and calculated and powerful but at the same time so tender and full of warmth. Where Voldemort was only capable of cruelty, Thanos showed compassion. He heard what the Titan has done. But he couldn’t shake the feeling that Thanos was no madman, but instead someone whose desire to fulfill his own vision had clouded his judgement. And he was so, so very Slytherin in that, that Severus couldn’t help but admire him. He spoke with such ardent belief in making the Universe a better place. But Severus was no fool, either. He was done serving men who thought the world of themselves. No, what he thought of Thanos was… different. Unlike anything he’s felt before. And that terrified him. 

Even now, as he was about to enter Thanos’s cell, he felt a weird sense of anticipation. Was he actually excited to see Thanos? Severus was tasked by whatever remained of the Order after the defeat of Voldemort with interrogating Thanos. Having worked with his fair share of egotistical maniacs, he was deemed perfect for the job. And as Thanos refused to speak, and Severus wasn’t allowed to… enhance… his interrogation, he simply visited Thanos everyday in his cell, and in each other’s company, the two men would simply talk. This day was no different from the others. When Severus entered the cell, the Titan was reading a book, but at the sound of Snape’s approach, he lifted his head and smiled. Something in Severus jumped at the thought that Thanos might like his visits, but he repressed the feeling immediately. 

“Severus.” The Titan said quite happily, as Snape put the stack of books he was carrying on Thanos’s bedside table. “Ah, yes. More entertainment.” Thanos said, as he examined the books. Severus moved over to where his usual chair stood and sat down with a heavy sigh. 

“Though I have got to admit.” Thanos continued silkily, “You are far more entertaining a book than any of the ones you’ve brought me.” Severus raised his eyebrow in surprise. For a moment he found himself at a lack for words, but he quickly recollected himself upon seeing the smirk playing on the other man’s face. 

“I’m hardly an open one.” Severus said coldly. “More skilled men than you have tried to read me.” To his surprise, Thanos never stopped smiling. And to his utter astonishment, Severus felt that excitement once again. As if they were… butterflies? In his stomach? But before he could ponder on what any of it meant, the Titan spoke again. 

“Nevertheless a most interesting one. I know I’d love to… see a chapter or two… maybe crumple a few pages in the process…” Thanos said, his eyes never leaving Snape’s. _ I should be uncomfortable _ Severus thought. _ He should be making me uncomfortable. _But he wasn’t. Severus’s emotions were now all over the place, though none of them seeped through his cold exterior as he spoke. 

“I’m sure they’re a lot bleaker than yours.” Snape said tentatively, eyeing the jarring purpleness of the Titan. But his desperate attempt to get Thanos talking failed miserably.   


Thanos laughed. “I like my color. Looks like you could use some of it in your life.” He said, blatantly staring at Severus, analyzing his black-clad figure up and down. If he wasn’t anemic, he’d probably blush. Thank Merlin for malnutrition. Severus swallowed hard. He could no longer mistake the heat in the Titan’s eyes. Something was brewing. And he wasn’t the Master this time. 

“This is all merely clothing. But you, I assume, are… this _ shade _… all over?” Severus said, now reciprocating the Thanos’s heated gaze. He waited for a response without flinching. He felt that if only he moved all the passion he kept inside would come pouring out. 

Thanos stood up slowly and looked down at Severus in his chair, his mouth agape now at the sight of the Titan’s full figure. When Thanos spoke, his voice was full of unfulfilled yearning as well as felt like a warm invitation. 

“_ How about you come over here and find out for yourself? _”


	2. Cell-bound Fun

**Notes for the Chapter:**

> This chapter is the only NSFW one.

Severus stood up and gulped audibly. So this was happening now, huh? His eyes scoured Thanos as the man was nearing him slowly. Alright, so he was quite attractive, in his own, alien way. And the tension was nearly palpable. Severus realized just how horny he was. He sighed in resignation. _ You know what? _ , he thought, _ This might as well happen. _

“Fine.” Said Snape, now calm and collected, but every inch as hot as before. “Undress.” 

Thanos chuckled. “Well since you’re asking so nicely.” And he did just that. 

He threw his clothes into a heap next to his bed, and stood before Severus stark naked. Snape couldn’t help but part his lips. _ Yummy _, he thought. 

And his eyes must’ve betrayed that thought, because Thanos smiled, and said “You know, Severus. I have many children.” He said, as he came so close to Severus he was now towering over him. “But you’re the only one I’ll let call me daddy.” 

And at that they kissed. And it was hot and wet and before he knew it, Severus could feel the other man’s erection burrowing into his stomach. They parted, and Severus looked down on the massive penis trapped between their two bodies. It was, indeed, also, very purple. Upon this inspection, Thanos spoke again. 

“You know, its color is not the only funny thing about it.” He said, and Severus looked up in surprise. Could it be…? No, that was ridiculous. Almost against his better judgement, Severus knelt before Thanos. He reached to stroke the erection before him, but there was no way he was fitting that into his hands, or anywhere else for that matter. After a few hesitant movements, he finally reached to lick Thanos’s cock. The bigger man moaned at the sensation, and Severus immediately backed off. Was this…? The taste… Severus’s mind was reeling. 

He moved to lick the head again and this time he was sure. He looked up at Thanos. 

“D-daddy.” He said shakily. “It tastes like blueberries.” He said, this time managing a full blush. 

“Yes.” Said Thanos calmly. “And I can give you much more, like you’ve never tasted before.” 

And so, he did. 


	3. A Colorful Union

This was it. Their big day. The decorations were all in place and the guests have all already arrived. Even Filch had to admit that he’s never seen Hogwarts this beautifully decorated before. The Great Hall was full of the most ornate decorations, pots and vases full of flowers, hanging from the walls and spread languidly in every corner. The theme of the wedding was a union between green and purple - one pertaining to Severus’s Slytherin soul and the other to Thanos’s uncanny skin shade. The chairs were a sight to behold, as well. They stood in rows, with a lane left empty in the middle, leading towards the flowery arch, but each and every single one was different from the other. Though they all matched in color, each was altered to fit the designated person’s special needs. And so Hagrid’s chair was big and comfy, and Rocket sat on a smaller one in the front row that allowed his racoon limbs to spread comfortably. 

Everyone was chatting and discussing the events of the last few months. The excitement in the room was evident, as the most unlikely of people sat together and formed circles, sharing their thoughts and stories. After the universe, or rather - all the universes - had collapsed on one another, there was no point in hiding magic any more. With the Avengers and Justice League roaming the skies of the Earth, magic was no longer something people would fear or vilify. And as such, the guests, now gathered in the Great Hall were the most absurd ensamble possible. 

In one corner, resting neatly on several cushions, was Albus Dumbledore’s portrait, busy chatting with Gandalf and Merlin, all three discussing the nature of magic as they knew it. Right next to them, Spock and Castiel seemed to be having a discussion on the habits of humans, and how being around them has appeared to have a long-lasting impact on their personality and world-view. On the other side of the room, John Watson and Rose Tyler ardently discussed the implications of being a “potential love-interest” and rising above the label of a “sidekick”, and laughed each time the other told a ridiculous story of their best friends’ unprecedented behavior.

The room began to settle down, as Captain Butch Flowers, who was to officiate the wedding, stood in the middle of the room, in front of everyone. He stood right behind a beautifully decorated arch, full of purple and green roses. Batman and Asra took their place as the bridesmaids next to the altar, as did Kylo Ren, filling his role as the Maid of Honor. Soon enough, Thanos entered the room. He was wearing a fully white suit that shone in the glimmering light of the sunset, as the last rays of the sun travelled through the Great Hall’s pointed windows to illuminate the scene. The last murmurs died within minutes, and the wedding march began to play. 

Severus began to enter the hall in a beautiful, black wizarding gown, holding a bouquet of green and purple lilies. He was led to the altar by no other than Minerva herself, her being his best and most trusted friend. Though the last years of his spying had put a strain on their relationship, they have since reconciled and were closer than ever before. Once they reached the altar, the ceremony began. And it was the most beautiful one that Hogwarts has ever seen. 

There were many tears at first, then there was cheering, and finally, partying. Several people congratulated the grooms throughout the night, but they both seemed too preoccupied with each other to pay people too much attention. As the wedding drew to a close, Severus sighed deeply. It was pleasant to be openly appreciated rather than hated for once in his life. But it was tomorrow that the real deal began. Tomorrow, they would leave for their honeymoon. 


	4. The Joys of Honeymoon

“And this is where the Red Skull led us, telling us the story of how he ended up here in the first place.” Said Thanos, as they climbed up the rocky mountain. It was their honeymoon, and to Thanos’s surprise, Severus had asked him to recreate his incredible feat of gathering the Infinity Stones as a leisure activity. He couldn’t hold it against him, if he was being honest. Getting those stones was a great victory, and he imagined any sane, power-hungry being would be willing to find out more about them. Finally they’ve reached the cliff edge of Vormir that demanded the biggest sacrifice off of Thanos. He stood at the edge looking downwards. 

“Yes. This is where I was forced to sacrifice Gamora. But surely, you must understand. We all make sacrifices in pursue of greatness.” He said, looking ahead the entire time. He feared he might tear up, and he abhorred the idea of anyone seeing him cry. 

“Indeed.” Said Severus from behind his back. He took a few more steps towards the Titan, so that now he was standing directly behind him, his hands resting on the larger man’s waist. “You know.” He began. “I’ve been conversing with that spider-boy, Peter Parker. I’m quite enthralled at just how innovative and linguistically unpredictable 21st century lingo is.” He paused for a moment, and shuffled in his feet. “What I’m saying is, he’s taught me quite a few useful phrases, and one, I think, is most appropriate for this occasion.” 

Thanos smiled. What wistful thought could that kid possibly instill in Severus’s mind? Severus stood on his toes, so that his lips were as close to Thanos’s ear as possible, as he said softly, his voice barely above a whisper:   
  
“Lmao, yeet.” 

And raising his leg, in one swift movement, he kicked Thanos off the cliff. When he woke up, covered in water, the soul stone rested neatly in the palm of his hand. 


	5. No More Secrets

“I just don’t understand why I always end up fucking people to get where I need to be.” He said, scowling, as he strolled across the hallway alongside Potter. At this point, he had no shame left. And Potter was no longer a student. He might as well ruin his psyche with some overly detailed spying stories, he decided. 

Harry winced audibly, but instead of retorting, he just said, “Well, a good spy takes advantage of all his best assets.” A small smile playing on his lips. 

Severus snorted. Maybe he hadn’t been giving the young man enough credit after all. 

“And Thanos, objectively, was a hunk. Too bad about Voldemort though.” Harry said, causing Severus to stop in his tracks. They’ve already reached the gargoyle that guarded the entrance the headmaster’s office, but he wasn’t letting that comment go. 

“What?!” Severus screeched. “You think I fucked Voldemort? What the fuck, Potter? That’s gross!” His voice so loud Harry felt it was drilling into his head. 

“Well you fucked Thanos! So how was I supposed to know?” He answered, raising his voice to at least try and match the other man’s. 

“You said yourself Thanos was a nice piece of ass!” Severus yelled back. 

“Alright, alright, yes, he was!” Said Harry, backing off, as they both took a couple of deep breaths. When they looked at each other again, the case was far from closed.   
  
“Who’d you fuck, then?” Harry asked, without hesitation. 

Severus sighed. “Lucius Malfoy.” He said, his face empty. 

“Oh. And his wife?” Inquired further Harry. 

“Yes. Lucius Malfoy and his wife. Both of them.” 

“OH.” Repeated Harry, this time more forcibly. “Well, they’re both, also, objectively attractive.” He said, giving a small smile. 

“Yes, Potter. I have impeccable taste.” Severus sneered, and Harry grinned. Together they turned towards the gargoyle to finally face the late Headmaster. 

***

“So Thanos is dead?” Albus asked, from behind his glasses. 

“Indeed.” Answered Severus, his neck already sore from having to look up at the portrait. 

“And Nick Fury has been informed?”

“Promptly.”

“His reaction?”

“He said, and I quote, ‘Serves that motherfucker right.’”

“How fitting. And the soul stone has been retrieved and is now stored safely, away from prying eyes?” 

“That is also correct, yes.” 

“Hmm.” Said the Headmaster, as he furrowed his brow. “I imagined that only sacrificing something you loved would work, and yet, you’ve succeeded. Unless, dear boy…” He looked at Snape with uncertainty, but before the man could say anything in protest, Potter’s angry snort interrupted them. 

“Right.” The young man said, visibly upset. “Just like Thanos loved Gamora? Sure, let’s glorify the love of abusers.” 

Both Severus and Albus looked at him expectantly, as if waiting for an explanation. Harry shuffled in his feet uncomfortably. “Look, all I’m saying is - the soul stone is full of shit, alright? Maybe you just have to sacrifice anything at all, but it says it has to be something you love to stop you from ever doing it and getting the stone.” He said, the fear of being ridiculed written all over his face. But upon seeing understanding and appreciation dawning on the faces of the other two, Harry relaxed. 

“Very well then.” Said Dumbledore finally. “I have just one more thing to ask Severus that is not necessarily appropriate for Harry’s ears, so if you could step out for a second my dear…”   
  
“Professor, you can’t-” Harry began, but Severus interrupted him immediately.   
  
“No.” He said determinedly. “We already established that whatever happens - we’re all in this together. We’re all adults now. Whatever it is, I’m not hiding anything from Potter ever again.” Severus said, feeling Harry’s eyes searching his face. He turned to look at the young man and he smiled in gratitude. 

“Fine.” Said Dumbledore, sounding eerily amused. “Stay then. But don’t say I didn’t warn you.” He added, and he bent forward in his armchair, as he looked Severus deep in the eye and finally asked, “Did his dick really taste like blueberries?”


End file.
